The Arizona Strip (Page 1 of 3)

Introduction

Mustang Point in the Grand Wash Cliffs. Photo by Coby Jordan.

The Arizona Strip encompasses five million acres of the far northwestern corner of Arizona north of the Colorado River and south of the Utah border [Map]. An arid, isolated, and sparse landscape, the region nonetheless has sustained a rich human history, from the 8000 year-old remains of Paleoindians to the creation of the million-acre Grand Canyon-Parashant National Monument in January of 2000.

Within the Strip lie several smaller provinces delineated by landscape features, namely a series of plateaus and tablelands stretching in roughly north-south directions. In the extreme northwest corner of the Strip, the only year-round stream in the area, the Virgin River, flows from southern Utah into Lake Mead, which borders the Strip at its southwestern corner. To the east lies a series of tablelands separated by escarpments and valleys.

The first is the Shivwits Plateau, a vast tableland extending from the Grand Canyon in the south, to the Hurricane Cliffs in the east, to the St. George basin in the north. East of the Shivwits are the Uinkaret Plateau, Antelope Valley, the Kanab Plateau, the Kaibab Plateau (reaching up to 9,200 feet), House Rock Valley, and the Paria Plateau. Marble Canyon of the Colorado River forms the eastern border of the Strip. Navajo Bridge, near Lees Ferry, provides the only Arizona access to the Strip, as the immense Grand Canyon of the Colorado River isolates this region from the rest of the state.

Past and Present Arizona Strip Biota

The Arizona Strip has an average elevation of 5,000 feet and is largely covered with pinyon-juniper woodlands and shrublands. Higher elevation areas, such as the Kaibab Plateau and isolated mountains such as Trumbull and Dellenbaugh support forests of ponderosa pine, aspen and fir. Lower elevation locales sustain desert vegetation such as cacti, creosote, and saltbrush, as well as chaparral-oak scrub communities. The Virgin River and occasional natural seeps and springs across the region support riparian species, including Fremont cottonwood, willow, and non-native tamarisk, as well as rare orchids and ferns.

Fauna of the Strip include over a hundred species of birds, including golden eagles, and recently released endangered California condors. Desert tortoises, desert mule deer, coyotes and bobcats are found in suitable habitats throughout the region. The Virgin River supports dwindling numbers of native fish such as Virgin River dace, woundfin, round-tailed chub, and Gila mountain-sucker. Desert bighorn sheep and pronghorn antelope were nearly extirpated from the Arizona Strip by the early 1900s. Re-introduction of bighorn sheep by the BLM and Arizona Game and Fish Department has resulted in a total population of 550 animals on the Strip as of 1996. Pronghorn have also benefited from re-introduction programs, with the largest population occurring in Antelope Valley, north of Mt. Trumbull. Among invertebrate species of the Strip are a number of endemic mollusks, including the Grand Wash springsnail and the endangered Kanab ambersnail.

Until the end of the Pleistocene, megafauna such as elephants, camels, Harrington's mountain goat, Shasta ground sloth, and giant Teratornis birds roamed the area we now call the Arizona Strip. The arrival of early humans to the Arizona Strip region is believed to have been a contributing factor in the extinction of the region's megafauna, in conjunction with significant changes in global climate, a shift known today as the Pleistocene-Holocene transition. Studies of packrat middens, plant remains, and atmospheric models suggest that winter precipitation increased, and that summer precipitation and temperatures decreased during this transition roughly 10,000 years ago. Vegetation change in response to the climate shift was swift on the Arizona Strip, as spruce, limber pine and dwarf juniper disappeared from areas of lower elevation (< 8,000 feet), to be replaced by better adapted plant species. Ponderosa pine, gambel oak, one-seed juniper and pinyon pine migrated to this portion of the Colorado Plateau by 7,000 years before present (B.P.), although contemporary vegetation communities were not fully established until 2,000-3,000 B.P.. Dendrochronological and palynological studies have allowed us to reconstruct past climate change events on the Colorado Plateau. These climatological fluctuations have had enormous influence on the patterns of human settlement and agriculture throughout the southwestern United States, particularly on marginal, arid lands, such as those of the Arizona Strip.

Follow these links to:
Page 2 - Landscape Changes and Human History:  1776 to Present
Page 3 - Life on the Arizona Strip Today
References